620 ENERGOPODA 



Cells. 



1 Costal {or mediastinal) cell. 



2 Subcostal cell. 



3 Marginal cell. 



4 Submarginal cell. 



4'"' Second submarginal {or cvhital) cell {or cubital fork-cell). Sometimes 

 a third submarginal cell is caused through a long recurrent veinlet 

 as in figs. 345, 347, 348, from near the base of e^ to d. 



5 First posterior {or suhaincal) cell. 



6 Discal cell. 



6" Second posterior cell. 

 6*" Third posterior cell. 

 6" Fourth posterior cell. 



7 Postical {or bth i^osterior) cell {or postical forh-cell). 



8 Axillary cell. 



9* Upper {or Ist) basal cell. 

 9^ Second {or middle) basal cell. 

 9c Anal {or lower, or Zrd basal) cell. 

 10 Alula. 



Notes on the Venation of the Asilid^. 



The general " facies " of the venation of the Asilidce is characteristic, and yet 

 presents but few striking peculiarities. 



The Subcostal Vein is unusually long and is only paralleled in the Apioceridce 

 a,nd Mj/daid(e ; it very commonly (^Isi/wicc and Laphrince) receives the radial vein 

 before its tip as in those two families, but whereas in them it also receives at least 

 the upper branch of the cubital fork it is in only two or three instances that this 

 happens in the Asilidce; it is also very unusual for the veins of any Asilidce to 

 exhibit the peculiar upcurving which is so characteristic of those two families. 

 In the Dasyjwgonince and Lepjtogastrince the subcostal vein is not so remarkably 

 long, nor does it (except in rare instances at the absolute wingmargin) receive the 

 radial vein before its tip, but still it is longer than in the TherevidcB and ends nearer 

 to the tip of the radial vein than to the tip of the mediastinal. 



The Pe^fueca is rather long and consequently very distinct from that of the 

 Mydaidce (except Mecjascehis) ; it starts before the middle of the upper basal cell and 

 consequently far before the base of the discal cell. 



The Discal Cell is always present, and is long and pentagonal, the long upper 

 side being almost a straight continuation of the basal stem of the discal vein ; it 

 always emits three veinlets (of which one may rarely be misplaced), though the 

 course of these veinlets (especially the lower one) may vary. 



The Posteeior Cells are always five (except in two small American genera, 

 Townsendia and Leptopteromyia), usually all open, but all subject to being closed 

 through connection between neighboring veins. 



The Small Ceoss-vein is usually present, but sometimes disappears and then the 

 upper branch of the postical fork touches the lower margin of the discal cell for 

 a short (never long) space. 



A peculiarity in venation occurs in a few genera {Promachus, Mallophora, etc.) 

 in which the upper branch of the cubital fork throws back from near its base a 

 recurrent veinlet which actually extends to the radial vein, so that the radial vein 

 appears to be forked soon after the emission of the cubital vein and the base of the 

 upper branch of the cubital fork looks like an ordinary cross-vein separating the 

 second submarginal cell into an inner and outer cell ; a recurrent veinlet of a some- 

 what similar nature is not uncommon in the Anthracince but only as an almost 

 upright branch to the radial vein. 



